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# Physics Electricity help

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1. I suck at everything to do with electricity apparently..
question:
Three identical resistors are connected across a potential difference V so that one of them is in
parallel with the other two which are connected in series. The power dissipated through the first
one, compared to the power dissipated by each of the other two, is approximately
A the same
B half as much
C twice as much
D four times as much

I thought the answer was A... :/ Help pls... can you explain the concept too please thanks. Also is this part of the new a-level spec or nah?
2. bump
I suck at everything to do with electricity apparently..
question:
Three identical resistors are connected across a potential difference V so that one of them is in
parallel with the other two which are connected in series. The power dissipated through the first
one, compared to the power dissipated by each of the other two, is approximately
A the same
B half as much
C twice as much
D four times as much

I thought the answer was A... :/ Help pls... can you explain the concept too please thanks. Also is this part of the new a-level spec or nah?
Well what can you say about the voltages in each branch, and how could we use this
4. (Original post by samb1234)
Well what can you say about the voltages in each branch, and how could we use this
Voltage is the same in the parallel part right? It's split between components in series?
Voltage is the same in the parallel part right? It's split between components in series?
So what is the voltage across one of the resistors in the branch with 2 resistors compared to the resistor in the other branch, and how can we relate this to power
6. Voltage will be... Split... so you'll have half in one resistor and half in the other... So if you had a voltage of 12V... you'd get 6V in one resistor nd 6V in the other. Assume Resistors are all 1 ohm...
P=V^2/R
so You'd get P = 36/1 = 36

In the parallel one you'd get... 12V
Then P=V^2/R
P = 144/1 = 144.

144/36...
OKAY i got it.. THANKS DUDE. =) Answer is D... Thanks a bunch

(Original post by samb1234)
So what is the voltage across one of the resistors in the branch with 2 resistors compared to the resistor in the other branch, and how can we relate this to power
Voltage will be... Split... so you'll have half in one resistor and half in the other... So if you had a voltage of 12V... you'd get 6V in one resistor nd 6V in the other. Assume Resistors are all 1 ohm...
P=V^2/R
so You'd get P = 36/1 = 36

In the parallel one you'd get... 12V
Then P=V^2/R
P = 144/1 = 144.

144/36...
OKAY i got it.. THANKS DUDE. =) Answer is D... Thanks a bunch
No problem, you could also have done it algebraically but plugging in numbers works too (i normally would do algebra first then plug some numbers into check) - voltage is double so since p is proportional to v^2 if voltage doubles power quadruples

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